The invention is directed to a method and an arrangement for the transmission of facsimile-encoded information between multimedia-capable communication terminal equipment as known for the transmission of data, video and audio signals and implement their transmission upon employment of a protocol according to ITU-T H.223 or, respectively, H.245 (the version of 11/1995 is meant).
The terminal equipment of telefax group 3 connectable to a communication network via analog interfaces are used mainly for the transmission of digital still pictures. The still pictures to be communicated over the telecommunication networks are composed of a great plurality of minute black and white mosaic squares of the same shape and size (called pixels). The original still pictures are either scanned by a scanner and resolved into black or white pixels or are generated by a computer as the result of a document/drawing production. First, they are compressed in order to reduce the quantity of information to be transmitted, and then they are divided into information blocks and communicated block-by-block via the telecommunication network. In the receiving telefax terminal equipment, the received information are decompressed and decoded into the original black and white pixels, wherewith an image that looks like the original is compiled (and therefore represents a xe2x80x9cfacsimilexe2x80x9d thereof). The received image is usually printed out on paper by the receiving terminal equipment or, in some cases, is presented on a display picture screen or stored on local, digital storage devices such as magnetic disk.
The method employed by terminal equipment of the telefax group 3 has been standardized according to the International Telecommunication Union (ITU) in the corresponding ITU-T recommendations for group 3 (ITU-T T.4, ITU-T T.6, ITU-T T.30) (last revision 1995 in the meantime).
A facsimile group 3 device is usually a xe2x80x9cmonomediaxe2x80x9d communication terminal equipment, i.e. it can normally only transmit one specific type of information (namely, a facsimile pixel image).
By comparison thereto, multimedia-capable communication terminal equipment are in the position of simultaneously transmitting two information types such as, for example, a facsimile pixel image accompanied with voice.
An object of the invention is to specify a method that is simple to realize for facsimile image transmission in the framework of multimedia communication via a communication network that enables the realization of auxiliary communication services regardless of whether the communication terminal equipment are connected to the communication network via analog or digital interfaces. Over and above this, arrangements for the implementation of such a method are to be specified.
This object is achieved by a method having the features of claim 1 or by a method having the features of claim 2. Beneficial developments are the subject matter of subclaims. Further, an arrangements [sic] for implementation of specific developments of the inventive method is recited in claim 5.
The invention is explained in greater detail below:
Instead of employing the known half-duplex or full-duplex (T.30 Annex C) protocol according to ITU-T T.30 in the information stream communicated between telefax terminal equipment, it is proposed to employ a new full-duplex protocol according to xe2x80x9cPacket Media Modexe2x80x9d of the ITU PSTN/mobile picture telephone (ITU-T H.324 or, respectively, ITU-T H.32P/M series of ITU-T recommendations) in which the facsimile protocol according to ITU-T T.30 is multiplex with voice (encoded, for example, according to ITU-T G.723, G.729 or G.dsvd) with ITU-T H.223. The control, i.e. opening, transmitting and closing the facsimile channels, ensues with the assistance of an ITU-T multimedia channel controller according to ITU-T H.245.
An inventive method for the transmission of facsimile-encoded information from a sending communication terminal equipment via a communication network to a receiving communication terminal equipment upon employment of the facsimile transmission protocol according to ITU-T T.4 and ITU-T T.30 and of a flexible PSTN/mobile picture telephone protocol (ITU-T H.223 in the meantime) with respect to the user channels can have the following method steps given facsimile group 3 transmission with half-duplex facsimile protocol according to ITU-T T.30:
1a) A digital facsimile input information is compressed in the sending communication terminal equipment;
1b) The facsimile-encoded (according to ITU-T T.4, T.6) information is divided by a facsimile matching layer and matched to the multimedia packet multiplex layer lying therebelow (FIG. 1). For this, two data channels (data channel #1 and #2) are allocated and opened with the assistance of ITU-T H.245. Data channel #2 is used as full-duplex channel for the transmission of the facsimile control data according to ITU-T T.30. Among others, the device parameters and the shared transmission parameters (for example, image resolution, facsimile compression method, error correction method, facsimile transmission or reception) are exchanged in this data channel, selected and set; the successful/or unsuccessful transmission of the page and/or the facsimile transmission is confirmed; the communication ended after transmission of the facsimile message and the control returned to ITU-T H.245. Data channel #1 is allocated and opened as half-duplex channel for the transmission of the facsimile encoded data.
According to the settings, the facsimile data are encoded and sent over data channel #2.
1c) Each data block of the data channel #2 and #1 is handed over to the multiplex layer identified as facsimile information control block or, respectively, facsimile information data block;
1d) All information data blocks are multiplexed by the sending communication terminal equipment with potentially existing, other information data blocks for voice, video, data, etc., with the assistance of the multiplex layer upon employment of a PSTN/mobile picture telephone protocol adapted with ITU-T H.223, are transmitted to the receiving communication terminal equipment and demultiplexed therein;
1e) The demultiplexed information data blocks are respectively assigned to a matching layer allocated to the information data type of video, voice, data or facsimile, the facsimile matching layer forwards the facsimile information blocks to the data channels #1 and #2 of the receiver for application of a facsimile decompression method according to ITU-T T.4, T.6, T.30, and the decompressed facsimile information is output or further-processed. Here as well as in the cases described below, the facsimile matching layer can also be part of a data matching layer.
2) The following method steps can be provided given facsimile group 3 transmission with the new, optional full-duplex facsimile protocol according to ITU-T T.30 Annex C:
2a) a digital facsimile input information is compressed in the sending communication terminal equipment;
2b) The facsimile-encoded (according to ITU-T T.4, T.6) information is divided by a facsimile matching layer and matched to the multimedia packet multiplex layer lying therebelow (FIG. 1). For this, only one data channel (data channel #1) is allocated and opened with the assistance of ITU-T H.245. Data channel #1 is also used as full-duplex channel for the transmission of the facsimile control data according to ITU-T T.30 Annex C. Among others, the device parameters and the shared transmission parameters (for example, image resolution, facsimile compression method, error correction method, facsimile transmission or reception) are exchanged in this data channel, selected and set; the successful/or unsuccessful transmission of the page and/or the facsimile transmission is confirmed; the communication ended after transmission of the facsimile message and the control returned to ITU-T H.245. In data channel #1, the channel according to T.30 Annex C is allocated, opened and sent for the transmission of the facsimile encoded data.
2c) Each data block of the data channel #1 is handed over to the multiplex layer identified as facsimile information data block;
2d) All information data blocks are multiplexed by the sending communication terminal equipment with potentially existing, other information data blocks for voice, video, data, etc., with the assistance of the multiplex layer upon employment of a PSTN/mobile picture telephone protocolxe2x80x94according to ITU-T H.223 and H.245xe2x80x94, are transmitted to the receiving communication terminal equipment and demultiplexed therein;
1e) The demultiplexed information data blocks are respectively assigned to a matching layer allocated to the information data type of video, voice, data or facsimile, the facsimile matching layer forwards the facsimile information blocks to the data channel #1 of the receiver for application of a facsimile decompression method according to ITU-T T.4, T.6, T.30, and the decompressed facsimile information is output or further-processed.
In addition to the identification for facsimile information data blocks and facsimile control data blocks, an identification for audio (voice), video, data and control information data blocks is also provided in a beneficial development. Preferably, the facsimile transmission protocol according to ITU-T T.4, T.6, ITU-T T.030 and the PSTN/mobile picture telephone protocol according to ITU-T H.223 adapted with ITU-T H.245 is employed.
A facsimile device for the implementation of an inventive method contains an image scanner means, a printer means, a fax modem, a communication controller according to ITU-T T.30 and H.245, a multimedia multiplexer (H.223) and a facsimile encoder/decoder means (ITU-T T.4, T.6, T.81, T.82) as well as an audio input/output means such as, for example, loudspeaker and microphone. Over and above this, an audio signal encoder/decoder means is provided for the compression and decompression of audio input/output signals. As warranted, a PC or a data display can also be present.